Vapor compression system for heating and cooling of vehicles

ABSTRACT

Reversible vapor compression system including a compressor ( 1 ), an interior heat exchanger ( 2 ), an expansion device ( 6 ) and an exterior heat exchanger ( 3 ) connected by means of conduits in an operable relationship to form an integral main circuit. A first means is provided in the main circuit between the compressor and the interior heat exchanger, and a second means is provided on the opposite side of the main circuit between the interior and exterior heat exchangers to enable reversing of the system from cooling mode to heat pump mode and vice versa.

FIELD OF THE INVENTION

The present invention relates to reversible vapor compression system forheating and comfort cooling of a vehicle cabin or passenger compartment,including at least a compressor, a flow reversing device, an interiorheat exchanger, a multi-function expansion device, an internal heatexchanger, an exterior heat exchanger, another multi-function expansiondevice, an auxiliary heat exchanger through which a coolant iscirculated and an accumulator connected in an operational relationshipto form a closed main circuit. The system is operating undertrans-critical or sub-critical conditions using any refrigerant and inparticular carbon dioxide. More specifically the system is related toreversible refrigeration/heat pump systems for vehicles operating withelectrical, internal combustion or hybrid drive systems.

DESCRIPTION OF PRIOR ART

In reversible vapor compression systems for mobile applications, it isdesirable to use waste heat from the drive system of the vehicle, and/orfrom ambient air, as a heat source for the vapor compression system whenit is operated in heat pump mode. The vehicle drive system may have oneor more engines, electric motors, fuel cells, power electronics unitsand/or batteries, all of which may give off waste heat.

Patent, DE19813674C1, discloses a reversible heat pump system forautomobiles where exhaust gas from the internal combustion engine isused as heat source. The disadvantage of this system is the possibilityof oil decomposition in the exhaust gas heat recovery heat exchanger(when not in use) as the temperature of the exhaust gas is relativelyhigh. Another disadvantage is the corrosion problems that may occur onthe exhaust-side in the heat recovery heat exchanger. A thirddisadvantage is the considerable size of the exhaust/refrigerant heatexchanger, and its vulnerable position under the vehicle. A fourthdisadvantage of this system is that the pressure in the high side of thecircuit cannot be controlled when the circuit is operated in heat pumpmode. This may give operational problems such as insufficient capacityand low efficiency. Finally, a fifth disadvantage of this system is theabsence of an internal heat exchanger in the circuit. Without this heatexchanger, the system will not achieve maximum capacity and efficiencyin cooling-mode operation at high ambient temperature.

Additionally a patent application, DE19806654, describes a reversibleheat pump system for motor vehicle powered by an internal combustionengine, where the engine coolant system is used as heat source. Thedisadvantage of this system is that it can only absorb heat from theengine coolant circuit, and at start-up, this may delay the heating-uptime of the engine coolant and the engine itself. Consequently, theengine needs more time to reach normal temperature, with increasedpollutant emission and fuel consumption as a likely result. In addition,the system may have to operate with extremely low evaporatingtemperature at start-up. Another disadvantage with this system is theinability to provide dehumidification of the passenger compartment airin heat pump mode, which may give reduced windshield defogging ordefrosting effect compared to a system with dehumidification options.

SUMMARY OF THE INVENTION

The present invention introduces a new improved vapor compression systemfor vehicle comfort cooling and heating where the said system canutilize waste heat both from the vehicle drive system and from ambientair as a heat source in heating mode, and as heat sink in cooling mode.The invention is characterized by the features as defined in theattached independent claim 1.

In some of its embodiments, as defined in the dependent claims 2-18, thesystem can offer dehumidification in heat pump mode. The system isprimarily intended for (but not limited to) use in vehicles having acoolant fluid circuit that exchanges heat with an internal combustionengine, an electric motor or a hybrid drive system.

The system can supply heat to the engine coolant circuit through theauxiliary heat exchanger for more rapid engine heating and to reduce theheat load on the exterior heat exchanger when the system is operated incooling mode. When operating in heat pump mode the system can use thecoolant system fully or partially as a heat source. The reversingprocess from heat pump to cooling mode operation, and vice versa, can beperformed by means of a flow reversing device and two multi-functionexpansion devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more details by way of examples and byreference to the following figures, where:

FIG. 1 is schematic representation of the First embodiment in heat pumpmode operation.

FIG. 2 is schematic representation of the First embodiment in coolingmode operation

FIG. 3 is schematic representation of the Second embodiment in heat pumpmode operation.

FIG. 4 is schematic representation of the Second embodiment in coolingmode operation

FIG. 5 is schematic representation of the Third embodiment in heat pumpmode operation.

FIG. 6 is schematic representation of the Third embodiment in coolingmode operation.

FIG. 7 is schematic representation of the Fourth embodiment in heat pumpmode operation.

FIG. 8 is schematic representation of the Fourth embodiment in coolingmode operation.

FIG. 9 is schematic representation of the Fifth embodiment in heat pumpmode operation.

FIG. 10 is schematic representation of the Fifth embodiment in coolingmode operation.

FIG. 11 is schematic representation of the Sixth embodiment in heat pumpmode operation.

FIG. 12 is schematic representation of the Sixth embodiment in coolingmode operation.

FIG. 13 is schematic representation of the Seventh embodiment in heatpump mode operation.

FIG. 14 is schematic representation of the Seventh embodiment in coolingmode operation.

FIG. 15 is schematic representation of the Eighth embodiment in heatpump mode operation.

FIG. 16 is schematic representation of the Eighth embodiment in coolingmode operation.

FIG. 17 is schematic representation of the Ninth embodiment in heat pumpmode operation.

FIG. 18 is schematic representation of the Ninth embodiment in coolingmode operation.

FIG. 19 is schematic representation of the Tenth embodiment in heat pumpmode operation.

FIG. 20 is schematic representation of the Tenth embodiment in coolingmode operation.

FIG. 21 is schematic representation of the Eleventh embodiment in heatpump mode operation.

FIG. 22 is schematic representation of the Eleventh embodiment incooling mode operation.

FIG. 23 is schematic representation of the Twelfth embodiment in heatpump mode operation.

FIG. 24 is schematic representation of the Twelfth embodiment in coolingmode operation.

FIG. 25 is schematic representation of the Thirteenth embodiment in heatpump mode operation.

FIG. 26 is schematic representation of the Thirteenth embodiment incooling mode operation.

FIG. 27 is schematic representation of the Fourteenth embodiment in heatpump mode operation.

FIG. 28 is schematic representation of the Fourteenth embodiment incooling mode operation.

FIG. 29 is schematic representation of the Fifteenth embodiment in heatpump mode operation.

FIG. 30 is schematic representation of the Fifteenth embodiment incooling mode operation.

FIG. 31 is schematic representation of the Sixteenth embodiment in heatpump mode operation.

FIG. 32 is schematic representation of the Sixteenth embodiment incooling mode operation.

FIG. 33 is schematic representation of the Seventeenth embodiment inheat pump mode operation.

FIG. 34 is schematic representation of the Seventeenth embodiment incooling mode operation.

DETAILED DESCRIPTION OF THE INVENTION

The disclosed vapor compression system is intended for (but not limitedto) use in vehicles, i.e. transport means such as automobiles, trains,trucks, buses and aircraft, where there is a need for cooling or heatingfor comfort purposes, and where some waste heat is available from thedrive system that may serve as a heat source when the vapor compressionsystem is operated in heat pump mode. The vehicle drive system mayinclude one or more of the following components: internal combustionengine, engine of other type, electric motor, fuel cells, batteries, andpower electronic systems, all of which need to reject some waste heatduring operation. In the disclosed system it is assumed that the drivesystem components reject heat through a coolant circuit where a coolantfluid is circulated through the drive system. The coolant circuit mayuse a single-phase fluid (liquid or gas) or it may use a two-phasefluid. Usually, the coolant system also contains a radiator where heatcan be rejected to ambient air. The disclosed vapor compression systemconsists of a refrigerant circuit containing an interior heat exchanger,an exterior heat exchanger, an auxiliary heat exchanger through whichthe coolant fluid is circulated, an internal heat exchanger whichexchanges heat inside the refrigerant circuit, an accumulator, acompressor, and flow-controlling devices. The interior heat exchangerabsorbs heat from the passenger compartment or cabin in comfort coolingmode, and transfers heat to the passenger compartment or cabin inheating mode. Heat may either be transferred directly to/from thepassenger compartment/cabin air that is circulated through the interiorheat exchanger, or heat may be transferred indirectly through asecondary fluid. The exterior heat exchanger absorbs heat from theambient air in heat pump mode, and rejects heat to ambient air incomfort cooling mode. Heat may either be transferred directly to/fromambient air that is circulated through the exterior heat exchanger, orheat may be transferred indirectly through a secondary fluid.

When the vehicle is started from cold conditions in low ambienttemperature, it is desirable to have a rapid heating up of the passengercompartment/cabin, and the drive system components should also reachnormal operating temperature as fast as possible. In order to achievethis, the disclosed system absorbs heat from ambient air through theexterior heat exchanger in the initial period of operation afterstart-up in heat pump mode. The drive system components are thus allowedto reach normal temperature quickly, since no heat is taken from thecoolant circuit. In fact, the added load on the drive system due to theheat pump compressor power requirements makes the temperature of thecomponents and the coolant fluid rise more rapidly. Heat is supplied tothe passenger compartment/cabin by the heat pump through the interiorheat exchanger. When the drive system components and the coolant circuittemperatures have reached a suitable temperature level, the heat pumpoperation is changed into using coolant as a heat source instead, byabsorbing heat from the coolant circuit through the auxiliary heatexchanger. Eventually, the heat pump may be switched off and thecabin/passenger compartment heated directly by the coolant circuitthrough a separate heat exchanger (heater core). It is also possible tooperate the heat pump system by a combination of ambient air and coolantas heat sources, and to heat the passenger compartment/cabin by acombination of interior heat exchanger and heater core. In someembodiments of the system, the interior heat exchanger can offerbi-functionality in heat pump mode, in that part of the heat exchangeris used to dehumidify the air by cooling it, whereas the remaining partof the interior heat exchanger serves as an air heater.

When the vehicle is started in high ambient temperature, it is desiredto reduce the passenger compartment/cabin air temperature as quickly aspossible, and the vapor compression system is then operated in comfortcooling mode. Heat is now absorbed from the passenger compartment/cabinair through the interior heat exchanger. If the coolant fluid and drivesystem temperature is lower than the desired level at start-up, wasteheat from the vapor compression system may be given off to the coolantcircuit through the auxiliary heat exchanger. This heat input to thecoolant circuit may allow the drive system components to reach optimumoperation temperature more rapidly. Heat may also be rejected from thevapor compression system to the coolant circuit when the drive systemcomponents are at their normal temperature level. By reducing heat loadon the exterior heat exchanger in this way, the vapor compression systemcapacity and efficiency may be improved. This mode of operation ofcourse depends on sufficient heat rejection capacity in the coolantcircuit radiator. The distribution of heat input between the auxiliaryheat exchanger and the exterior heat exchanger can be controlled bybypass arrangements and flow-control devices.

The vapor compression circuit is switched between heat pump mode andcomfort cooling mode, and between varying modes of heat absorption andheat rejection, by using flow-reversing devices, flow-diverting devices,and multi-function expansion devices. The flow-reversing devices may befour-way valves, combinations of three-way valves, or other flowarrangements providing reversing of the flow direction in the circuit.The flow-diverting devices may be three-way valves, combinations ofordinary valves, or other flow arrangements providing diversion of flowbetween two branches in the flow circuit. The multi-function expansiondevices provide refrigerant expansion in one direction and unrestrictedflow in one or both directions, depending on the mode of operation. Themulti-function expansion devices may include any combination ofthrottling means, expansion machines or turbines with or without workrecovery, and flow control means.

1. FIRST EMBODIMENT

The First embodiment of the present invention for a reversible vaporcompression cycle is shown schematically in FIG. 1 in heat pump mode andFIG. 2 for comfort cooling operation. In accordance with the presentinvention, the device includes a compressor 1, a flow-reversing device6, an interior heat exchanger 2, a multi-function expansion device 9, aninternal heat exchanger 4, an exterior heat exchanger 3, anothermulti-function expansion device 8, an auxiliary heat exchanger 7 and anaccumulator 5. The system operation in heat pump and cooling mode isdescribed with reference to FIG. 1 and FIG. 2 respectively.

Heat Pump Operation (FIG. 1):

When the system is running as heat pump, the compressed refrigerantafter the compressor flows first through a flow-reversing device 6 thatis in heating mode. The refrigerant then enters the interior heatexchanger 2, giving off heat to the heat sink (cabin/passengercompartment air, or secondary fluid) before passing through themulti-function expansion device 9 which is open, i.e. the pressurebefore and after is basically the same. The high-pressure refrigerantthen passes through the internal heat exchanger 4 where its temperature(enthalpy) is reduced by exchanging heat with low-pressure refrigerant.The cooled high-pressure refrigerant then enters exterior heat exchanger3 before its pressure is reduced to the evaporation pressure by themulti-function expansion device 8. The low-pressure refrigerant entersthe auxiliary heat exchanger 7 where it evaporates by absorbing heat.The amount of heat absorbed in the auxiliary heat exchanger 7 andexterior heat exchanger 3 can be controlled by controlling coolant fluidand/or air flow rate respectively. The refrigerant then passes throughthe flow-reversing device 6, the low-pressure accumulator 5 and theinternal heat exchanger 4 respectively, before it enters the compressor,completing the cycle.

Cooling Mode Operation (FIG. 2):

The flow-reversing device 6 will now be in cooling mode operation suchthat the interior heat exchanger 2 acts as evaporator while the exteriorheat exchanger 3 act as heat rejector (condenser/gas cooler). In thismode, the compressed gas after compressor 1 passes through theflow-reversing device 6 before entering auxiliary heat exchanger 7.Depending on whether auxiliary heat exchanger 7 is in operation (forexample during start-up period in order to get the engine temperature upto normal temperature which can reduce the emission of undesired gaseswhich is typical for internal combustion engine), the high-pressurerefrigerant can be cooled down before it passes through themulti-function expansion device 8 without substantial pressure reduction(the pressure before and after remains basically constant). Thehigh-pressure refrigerant then enters the exterior heat exchanger 3where it is cooled down by giving off heat to the heat sink. Therefrigerant is further cooled down in the internal heat exchanger 4before its pressure is reduced to evaporation pressure by themulti-function expansion device 9. The low-pressure refrigerantevaporates by absorbing heat in the internal heat exchanger 2. Therefrigerant then passes through the flow-reversing device 6, accumulator5 and the internal heat exchanger 4 respectively, before it enters thecompressor 1, completing the cycle.

2. SECOND EMBODIMENT

The second embodiment is shown schematically in FIG. 3 and FIG. 4 inheat pump and cooling mode respectively. The main difference betweenthis embodiment and the First embodiment is the presence of a bypassconduit 24 providing a valve 12 which add the option to bypass theexterior heat exchanger 3 if needed.

3. THIRD EMBODIMENT

FIG. 5 and FIG. 6 show schematic representation of this embodiment inheat pump and cooling mode operation respectively. Compared to the Firstembodiment, it has an additional conduit and flow-diverting device 19for bypassing the internal heat exchanger 4. It is also possible toprovide a bypass conduit 25 in order to bypass the exterior heatexchanger 3 as in the Second embodiment. Under very low ambient (heatsource) temperature (low evaporation temperature), it might be desirableto avoid too high discharge temperature. In such cases, the refrigerantafter the multi-function expansion device 9 is totally or partiallydiverted by the flow-diverting device 19 in order to bypass the internalheat exchanger 4. The reversing process from heating mode to coolingmode operation is performed by using the two multi-function expansiondevices 8 and 9 as described in the First embodiment.

4. FOURTH EMBODIMENT

The Fourth embodiment is shown schematically in FIG. 7 and FIG. 8 inheat pump and cooling mode respectively. The main difference betweenthis embodiment and the First embodiment is the presence of a bypassconduit 28 providing a valve 12 which add the option to bypass theauxiliary heat exchanger 7 if needed.

5. FIFTH EMBODIMENT

FIG. 9 and FIG. 10 show schematic representation of this embodiment inheat pump and cooling mode operation respectively. Compared to the Firstembodiment, it has an additional multi-function expansion device 9′which is placed between the exterior heat exchanger 3 and internal heatexchanger 4. This embodiment represents an improvement of the Firstembodiment since the presence of the multi-function expansion device 9′between the exterior heat exchanger 3 and internal heat exchanger 4 addnew flexibility to the system. In heat pump mode, one can choose toexpand the refrigerant after the multi-function expansion device 9′which makes the exterior heat exchanger 3 function as heat absorber(evaporator) or to run the said heat exchanger and the auxiliary heatexchanger 7 at different evaporation temperature. This can be done byfirst reducing the pressure of the refrigerant to the (first)evaporation temperature in the exterior heat exchanger 3 by themulti-function expansion device 9′ and then reducing the refrigerantpressure by the multi-function expansion device 8 to the (second andlower) evaporation temperature in the auxiliary heat exchanger 7. Itwill also be possible for the refrigerant to flow through the saidexpansion device 9′ without any substantial pressure reduction such thatthe refrigerant can give off heat to the exterior heat exchanger 3before its pressure is reduced by the multi-function expansion device 8.The low-pressure refrigerant then enters the auxiliary heat exchanger 7,which function as heat absorber (evaporator).

6. SIXTH EMBODIMENT

FIG. 11 and FIG. 12 show schematic representation of this embodiment inheat pump and cooling mode operation respectively. Compared to the Firstembodiment, the multi-function expansion valve 8 is moved to theopposite side of the exterior heat exchanger 3. As a result, theexterior heat exchanger 3 will function as evaporator in heating mode.This can be beneficial in situations where the system can use theambient air as heat source during start-up until the engine temperaturecan reach normal operating temperature, after which, the excess heatfrom engine cooling system can be used as heat source. The reversingprocess from heating mode to cooling mode operation is performed byusing the two multi-function expansion devices 8 and 9 as described inthe First embodiment. In cooling mode operation, the pressure reductionwill be carried out by the multi-function expansion device 9 as in theFirst embodiment.

7. SEVENTH EMBODIMENT

FIG. 13 and FIG. 14 show schematic representation of this embodiment inheat pump and cooling mode operation respectively. Compared to the Sixthembodiment the auxiliary heat exchanger 7 is in a separate conduitbranch 26 coupled in parallel relative to the exterior heat exchanger 3by using an additional multi function expansion device 20 provided in abypass conduit. The system operation in heat pump and cooling mode isdescribed with reference FIG. 13 and FIG. 14 respectively.

Heat Pump Operation (FIG. 13):

When the system is running as heat pump, the compressed refrigerantafter the compressor flows first through a flow-reversing device 6 thatis in heating mode. The refrigerant then enters the interior heatexchanger 2, giving off heat to the heat sink before passing through themulti-function expansion device 9 which is open, i.e. the pressurebefore and after is basically the same. The high-pressure refrigerantthen passes through the internal heat exchanger 4 where its temperature(enthalpy) is reduced by exchanging heat with low-pressure refrigerant.The cooled high-pressure refrigerant after internal heat exchanger canthen be divided into two branches. If needed, some of the refrigerant isdiverted toward auxiliary heat exchanger 7 provided in parallel with theexterior heat exchanger 3. The pressure of the said refrigerant is thenreduced to evaporation pressure before said auxiliary heat exchanger 7by the additional multi function expansion device 20. The refrigerantfrom the auxiliary heat exchanger 7 is then directed into the inlet ofthe accumulator 5. The rest of the cooled high-pressure refrigerantflows through the multi-function expansion device 8 by which itspressure is reduced to the evaporation pressure. The low-pressurerefrigerant then enters exterior heat exchanger 3 where it evaporates byabsorbing heat. The refrigerant then passes through the flow-reversingdevice 6 before or after it is mixed with any refrigerant from auxiliaryheat exchanger 7 and enters the accumulator 5. The refrigerant thenflows through the internal heat exchanger 4 before it enters thecompressor 1, completing the cycle.

Cooling Mode Operation (FIG. 14):

The flow-reversing device 6 will now be in cooling mode operation suchthat the interior heat exchanger 2 acts as evaporator while the exteriorheat exchanger 3 as heat rejecter (condenser/gas cooler). In this mode,the compressed gas after compressor 1 passes through the flow-reversingdevice 6 before entering the exterior heat exchanger 3 where it iscooled down by giving off heat before it passes through themulti-function expansion device 8 without throttling (the pressurebefore and after remains basically constant). It will be also possibleto give off some heat in the auxiliary heat exchanger 7 by divertingsome refrigerant through the multi function expansion device 20. Thehigh-pressure refrigerant is further cooled down in the internal heatexchanger 4 before its pressure is reduced to evaporation pressure bythe multi-function expansion device 9. The low-pressure refrigerantevaporates by absorbing heat in the internal heat exchanger 2. Therefrigerant then passes through the flow-reversing device 6 before it ismixed with any of the refrigerant from the auxiliary heat exchanger 7before it enters the accumulator 5. The refrigerant then passes theinternal heat exchanger 4 before it enters the compressor 1, completingthe cycle.

8. EIGHTH EMBODIMENT

The Eighth embodiment is shown schematically in FIG. 15 in heat pumpmode and FIG. 16 in cooling mode operation. Compared to the Seventhembodiment, this embodiment represents a two stage compression systemwhere the refrigerant from the auxiliary heat exchanger 7 is directed tothe discharge side of the first stage compressor 1 through a circuitloop 22 before it is compressed by the second stage compressor 1″. As aresult, the evaporation pressure in the auxiliary heat exchanger 7 willbe independent and it will correspond to the intermediate pressure (thepressure after the first stage compressor 1). The reversing process fromheating mode to cooling mode operation is performed as described in theSeventh embodiment.

9. NINTH EMBODIMENT

The Ninth embodiment is shown schematically in FIG. 17 in heat pump modeand FIG. 18 in cooling mode operation. Compared to the Eighth embodimentthis embodiment has an additional inter-cooling heat exchanger 19provided in an additional circuit loop 23 which at one end is connectedto the circuit loop 22 prior to the auxiliary heat exchanger 7 and atthe other end to the circuit loop 22 after the heat exchanger 7 and avalve 21 provided in the circuit loop 22 between the expansion device 20and the auxiliary heat exchanger 7. In heating mode the valve 21 will beopen and some of the refrigerant after the expansion device 20 isdiverted to the inter-cooling heat exchanger 19 where the saidrefrigerant is evaporated in heat exchange with high pressure afterinternal heat exchanger 4. In cooling mode the valve 21 will be closedand refrigerant after expansion device 20 will flow through theinter-cooling heat exchanger 19 where it evaporates in heat exchangewith high pressure refrigerant after the multi-function expansion device8. In both cases, it results in de-superheating of the discharge gasafter first stage compressor 1 that results in lower specific work ofcompression and better system performance. The reversing process fromheating mode to cooling mode operation is performed as described in theEighth embodiment .

10. TENTH EMBODIMENT

The Tenth embodiment is shown schematically in FIG. 19 in heat pump modeand FIG. 20 in cooling mode operation. Compared to the First embodiment,the only difference is the location of the multi-function expansionvalve 9 where in this embodiment it is placed between the exterior heatexchanger 3 and the internal heat exchanger 4. It is also possible toprovide a bypass conduit in order to bypass the exterior heat exchanger3 as in the Second embodiment. In heat pump mode, expansion may thustake place in multi-function expansion device 9 to absorb heat in theexterior heat exchanger 3, or expansion may take place in multi-functionexpansion device 8 to absorb heat in the auxiliary heat exchanger 7. Inthe latter case it would be possible to bypass the exterior heatexchanger 3 using a bypass conduit (not shown in the figure) as in theSecond embodiment. Thus, the heat source may be ambient air duringstart-up, and then switched to engine coolant when the coolanttemperature has reached an acceptable level. During cooling modeoperation, the pressure on both sides of the internal heat exchanger 4will be basically the same with no temperature driving force forexchange of heat. As a result, the internal heat exchanger 4 will beactive only in one operational mode, either cooling mode or heat pumpoperation. The reversing process is performed as in the Firstembodiment.

11. ELEVENTH EMBODIMENT

FIG. 21 and FIG. 22 show schematic representation of this embodiment inheat pump and cooling mode operation respectively. Compared to the Firstembodiment, it incorporate an additional dehumidification heat exchanger2′ provided in a third circuit loop 25 which at one end is connected tothe main circuit between the flow reversing device 6 and auxiliary heatexchanger 7 and at the other end is connected between the internal heatexchanger 4 and interior heat exchanger 2, two check valves 11 and 11′provided in a fourth circuit loop 24 between the main circuit and thethird circuit loop 25, and a valve 10 (for example solenoid valve)provided in the third circuit loop 25. The system operation in heat pumpand cooling mode is described with reference to FIG. 21 and FIG. 22respectively.

Heat Pump Operation (FIG. 21):

In heat pump mode operation, the compressed refrigerant after thecompressor flows first through the flow-reversing device 6 that is inheating mode. The refrigerant then enters the interior heat exchanger 2,giving off heat to the heat sink. The high-pressure refrigerant passesthrough the check valve 11 and the then through the internal heatexchanger 4 where its temperature (enthalpy) is reduced by exchangingheat with low-pressure refrigerant. The cooled high-pressure refrigerantthen enters exterior heat exchanger 3 before its pressure is reduced tothe evaporation pressure by the multi-function expansion device 8. Itwould also be possible to bypass the exterior heat exchanger 3 using abypass conduit (not shown in the figure) as in the Second embodiment.The low-pressure refrigerant enters the auxiliary heat exchanger 7 whereit evaporates by absorbing heat. When the dehumidification heatexchanger 2′ is on, some of the high-pressure refrigerant after thecheck valve 11 is bled off by the multi-function expansion device 9 intothe dehumidification heat exchanger 2′ where it is evaporated, therebydehumidifying the interior air. The low-pressure refrigerant passesthrough the valve 10 that is open and is mixed with refrigerant from theauxiliary heat exchanger 7. The refrigerant then passes through theflow-reversing device 6, accumulator 5 and the internal heat exchanger 4respectively, before it enters the compressor, completing the cycle.

Cooling Mode Operation (FIG. 22):

The flow-reversing device 6 will now be in cooling mode operation suchthat the interior heat exchanger 2 and the dehumidification heatexchanger 2′ together act as evaporator while the exterior heatexchanger 3 as heat rejecter (condenser/gas cooler). In this mode, thecompressed gas after compressor 1 passes through the flow-reversingdevice 6 before entering auxiliary heat exchanger 7. Depending onwhether auxiliary heat exchanger 7 is in operation the high-pressurerefrigerant can be cooled down before it passes through themulti-function expansion device 8 without throttling (the pressurebefore and after remains basically constant). The high-pressurerefrigerant then enters the exterior heat exchanger 3 where it is cooleddown by giving off heat. The refrigerant is further cooled down in theinternal heat exchanger 4 before its pressure is reduced to evaporationpressure by the multi-function expansion device 9. The low-pressurerefrigerant evaporates by absorbing heat first in the dehumidificationheat exchanger 2′. It then passes through check valve 11′ (valve 10 isclosed) before it is further evaporated in the interior heat exchanger2. The refrigerant then passes through the flow-reversing device 6,accumulator 5 and the internal heat exchanger 4 respectively, before itenters the compressor, completing the cycle.

12. TWELFTH EMBODIMENT

The Twelfth embodiment is shown schematically in FIG. 23 in heat pumpmode and FIG. 24 in cooling mode operation. Compared to the Sixthembodiment, it incorporate an additional dehumidification heat exchanger2′ as for the tenth embodiment, but the one end of the interior heatexchanger is now connected with the main circuit through a conduit 27between the exterior heat exchanger 3 and the internal heat exchanger 4and the dehumidification heat exchanger 2′ is connected with theinternal heat exchanger 4. In addition to the check valve 11′ providedin the fourth circuit loop 24, a check valve 11″ is provided in theconduit 27.

In terms of operation and compared to the Eleventh embodiment, the onlydifference is the location of the multi-function expansion valve 9 wherein this embodiment it is placed between the exterior heat exchanger 3and the internal heat exchanger 4. In heat pump mode, expansion may thustake place in multi-function expansion device 9 to absorb heat in theexterior heat exchanger 3, or expansion may take place in multi-functionexpansion device 8 to absorb heat in the auxiliary heat exchanger 7 inwhich case it would be possible to bypass the exterior heat exchanger 3using a bypass conduit (not shown in the figure) as in the Firstembodiment. Thus, the heat source may be ambient air during start-up,and then switched to engine coolant when the coolant temperature hasreached an acceptable level. During cooling mode operation, the pressureon both sides of the internal heat exchanger 4 will be basically thesame with no temperature driving force for exchange of heat. As aresult, the internal heat exchanger 4 will be active only in oneoperational mode, either cooling mode or heat pump operation. Thereversing process from heat pump mode to cooling mode operation isperformed as described in the Eleventh embodiment.

13. THIRTEENTH EMBODIMENT

FIG. 25 and FIG. 26 show schematic representation of this embodiment inheat pump and cooling mode operation respectively. Compared to Eleventhembodiment, the only difference is the addition of a by-pass valve 12,which enables the refrigerant to by-pass the auxiliary heat exchanger 7if needed.

14. FOURTEENTH EMBODIMENT

The Fourteenth embodiment is shown schematically in FIG. 27 in heat pumpmode and FIG. 28 in cooling mode operation. This is embodiment isbasically the same as the Twelfth embodiment except for the location ofcheck valve 11 which has been replaced by another check valve 11′″,between the outlet of the dehumidification heat exchanger 2′ and inletof the interior heat exchanger 2. The reversing of system operation fromcooling mode to heat pump mode is performed as in the Twelfthembodiment.

15. FIFTEENTH EMBODIMENT

FIG. 29 and FIG. 30 show schematic representation of the Fifteenthembodiment in heat pump and cooling mode operation respectively.Compared to previous embodiments, the main difference lies in the waythe reversing is performed. In this embodiment, the flow-reversingdevice 6 has been replaced by two flow-diverting devices 13 and 14. Thesystem operation in heat pump and cooling mode is described withreference to FIG. 29 and FIG. 30 respectively.

Heat Pump Operation (FIG. 29):

In heat pump mode operation, the flow-diverting devices 13 and 14 are inheating mode. The compressed refrigerant after the compressor flowsfirst through the flow-diverting device 13 before entering interior heatexchanger 2, giving off heat to the heat sink. The high-pressurerefrigerant passes through the check valve 11′ and the then through theinternal heat exchanger 4 where its temperature (enthalpy) is reduced byexchanging heat with low-pressure refrigerant. The pressure of therefrigerant is reduced to the evaporation pressure by the multi-functionexpansion device 8 before it enters exterior heat exchanger 3. When thedehumidification heat exchanger 2′ is on, some of the high-pressurerefrigerant after the check valve 11′ is bled by the multi-functionexpansion device 9 into the dehumidification heat exchanger 2′ where itis evaporated, dehumidifying the interior air. The low-pressurerefrigerant passes through the valve 10 that is open before it is mixedwith refrigerant from the exterior heat exchanger 3. The refrigerantthen passes through the flow-diverting device 6, accumulator 5 and theinternal heat exchanger 4 respectively, before it enters the compressor,completing the cycle.

Cooling Mode Operation (FIG. 30):

In heat pump mode operation, the flow-diverting devices 13 and 14 are incooling mode such that the interior heat exchanger 2 and thedehumidification heat exchanger 2 acts as evaporator while the exteriorheat exchanger 3 heat rejecter (condenser/gas cooler). In this mode, thecompressed gas after compressor 1 passes through the flow-divertingdevice 13 before entering exterior heat exchanger 3. The high-pressurerefrigerant then passes through the multi-function expansion device 8without throttling (the pressure before and after remains basicallyconstant). The refrigerant then enters the internal heat exchanger 4where it is cooled down by giving off heat to the low-pressurerefrigerant on the other side of the heat exchanger. The pressure of therefrigerant is then reduced to evaporation pressure by themulti-function expansion device 9. The low-pressure refrigerantevaporates by absorbing heat first in the dehumidification heatexchanger 2′. It then passes through check valve 11′″ (valve 10 isclosed) before it is further evaporated in the interior heat exchanger2. The refrigerant then passes through the flow-diverting device 6,accumulator 5 and the internal heat exchanger 4 respectively, before itenters the compressor, completing the cycle.

16. SIXTEENTH EMBODIMENT (FIGS. 31 AND 32)

This embodiment includes a compressor 1, a flow-reversing device 6, aninterior heat exchanger 2, a multi function expansion device 17, anintermediate pressure accumulator 15, an internal heat exchanger 4, anexterior heat exchanger 3, two multi-function expansion devices 8 and 9,and an auxiliary heat exchanger 7. The system operation in heat pump andcooling mode is described with reference to FIG. 31 and FIG. 32respectively.

Heat Pump Operation (FIG. 31):

The compressed refrigerant after the compressor flows first through aflow-reversing device 6 that is in heating mode. The refrigerant thenenters the interior heat exchanger 2, giving off heat to the heat sinkbefore passing through the expansion device 9 by which the refrigerantpressure is reduced to intermediate pressure. The expansion device canbe open in which case there would be no pressure reduction by the saidexpansion device, and the pressure in the internal heat exchanger 4 andthe exterior heat exchanger 3 will be basically the same as intermediatepressure. The refrigerant pressure is then reduced to evaporationpressure before the auxiliary heat exchanger 7 by the multi-functionexpansion device 8. The low-pressure vapor then flows through the flowreversing device 6 before entering internal heat exchanger 4 andcompressor 1 at the end. In case there would be some pressure reductionin the multi function expansion device 17, the pressure in the internalheat exchanger 4 and exterior heat exchanger 3 will be somewhere inbetween pressure in the intermediate accumulator 15 and the evaporationpressure in the auxiliary heat exchanger 7. In both cases it would bepossible to bypass the internal heat exchanger 4 and exterior heatexchanger 3 or both, using a bypass conduit (not shown in the figures).

Cooling Mode Operation (FIG. 32):

The flow-reversing device 6 will now be in cooling mode operation suchthat the interior heat exchanger 2 acts as evaporator while the exteriorheat exchanger 3 as heat rejecter (condenser/gas cooler). In this mode,the compressed gas after compressor 1 passes through the flow-reversingdevice 6 before entering auxiliary heat exchanger 7. Depending onwhether auxiliary heat exchanger 7 is in operation the high-pressurerefrigerant can be cooled down before it passes through themulti-function expansion device 8 without throttling (the pressurebefore and after remains basically constant). The high-pressurerefrigerant then enters the exterior heat exchanger 3 where it is cooleddown by giving off heat. The refrigerant then flows through the internalheat exchanger 4 where it is further cooled down before its pressure isreduced to the accumulator pressure by the multi function expansiondevice 17. After the accumulator, the refrigerant pressure is reduced bythe expansion device 9 to the evaporation pressure in the interior heatexchanger 2. The low-pressure refrigerant evaporates by absorbing heatin the said heat exchanger. Afterward, the refrigerant passes throughthe flow-reversing device 6 and the internal heat exchanger 4respectively, before it enters the compressor, completing the cycle.

17. SEVENTEENTH EMBODIMENT

FIG. 33 and FIG. 34 show schematic representations of the Seventeenthembodiment in heat pump and cooling mode operation, respectively. Themain difference between this embodiment and Sixteenth embodiment is thatthe compression process is carried out in two stages by two compressors1 and 1″. The discharge refrigerant gas from the first stage compressor1 is directed into the intermediate pressure accumulator that result inde-superheating of the said refrigerant. As a result, the suction gasfor the second stage compressor 1″ can be saturated or close tosaturated, which compared to one stage compression (Sixteenthembodiment), results in a lower specific compression work. The operationof the system in heating and cooling mode is otherwise the same as inSixteenth embodiment.

It is also understood that the accumulator presented in differentfigures is a schematic representation where the actual solution coulddiffer from those shown in these figures.

1-14. (canceled)
 15. A reversible vapor compression system for heatingand comfort cooling of a vehicle cabin or passenger compartment,including at least a compressor (1), a flow reversing device (6), aninterior heat exchanger (2), a multi-function expansion device (9), aninternal heat exchanger (4), an exterior heat exchanger (3), anothermulti-function expansion device (8), an auxiliary heat exchanger (7)through which a coolant is circulated and an accumulator (5) connectedin an operational relationship through conduits to form a closed maincircuit, wherein the inter-connection of the components (1, 2, 3, 4, 5,6, 7, 8, 9) of the system are provided such that ambient air and coolantcirculated from the vehicle drive system can both partially or fully beused as heat source and heat sink in heat pump mode and comfort coolingmode, respectively.
 16. System according to claim 15, wherein thereversing process from heat pump to comfort cooling mode operation, andvice versa, is performed by means of a flow reversing device (6)connected to the high pressure side of the compressor (1) and the inletof the accumulator (5) and two multi-function expansion devices (8) and(9) provided in the circuit respectively between the auxiliary heatexchanger (7) and exterior heat exchanger (3) and between the interiorheat exchanger (2) and internal heat exchanger (4).
 17. System accordingto claim 15, wherein the reversing process from heat pump to comfortcooling mode operation, and vice versa, is performed by means of a flowreversing device (6) connected to the high pressure side of thecompressor (1) and the inlet of the accumulator (5), and threemulti-function expansion devices (8, 9) and (9)′, where expansion takesplace in the multi-function expansion device (9)′ between the internalheat exchanger (4) and exterior heat exchanger (3) when ambient air or acombination of ambient air and coolant is used as heat source in heatpump mode, and expansion takes place in the multi-function expansiondevice (8) between auxiliary heat exchanger (7) and exterior heatexchanger (3) when coolant is used as the only heat source.
 18. Systemaccording to claim 15, wherein an additional bypass conduit (24)including a valve (12) is provided in parallel with the exterior heatexchanger (3).
 19. System according to claim 15, wherein a furtherbypass conduit (25) and flow-diverting device (19) for bypassing theinternal heat exchanger (4) is provided in parallel with the internalheat exchanger (4).
 20. System according to claim 15, wherein themulti-function expansion device (8) is placed between the exterior heatexchanger (3) and the internal heat exchanger (4).
 21. System accordingto claim 20, wherein the auxiliary heat exchanger (7) is connected by aconduit in parallel relative to exterior heat exchanger (3), with anexpansion device (20) provided on the up stream side of the auxiliaryheat exchanger when the system is in heating mode operation.
 22. Systemaccording to claim 21, wherein the compression is performed by twocompressors (1) and (1″) in two stages and that the refrigerant from theauxiliary heat exchanger (7) is mixed with the discharge refrigerantfrom compressor (1) through a circuit loop (22).
 23. System according toclaim 22, wherein an additional inter-cooler heat exchanger (19) isprovided in an additional circuit loop (23) between the circuit loop,(22) prior to the auxiliary heat exchanger (7) and expansion device(20), and the interconnection of the compressors (1, 1′) and that avalve (21) is provided in the circuit loop (23) to control the flowthrough the inter-cooler heat exchanger (7).
 24. System according toclaim 22, wherein the two-stage compressors (1, 1′) are in the form of asingle compound compressor.
 25. System according to claim 15, whereinthe multi-function expansion device (9) is placed between the internalheat exchanger (4) and the exterior heat exchanger (3).
 26. Systemaccording to claim 15, wherein an additional dehumidification heatexchanger (2′) provided in a third conduit loop (26) which at one end isconnected to the main circuit between the accumulator (5) and auxiliaryheat exchanger (7) and the other end between the internal heat exchanger(4) and interior heat exchanger (2), two check valves (11) and (11′)provided in a fourth conduit loop (27) between the main circuit andthird conduit loop (26) and a valve (10) provided in the third loop(26), whereby the dehumidification heat exchanger (2′) and the interiorheat exchanger (2) are connected in series in cooling mode operationwhereas in heating mode, the same said dehumidification heat exchanger(2)′ will dehumidify the air before it is heated up by the interior heatexchanger (2).
 27. System according to the claim 15, wherein anintermediate accumulator (15) is provided in the main circuit betweenthe internal heat exchanger (4) and multi function expansion device (9)and that another multifunction expansion device (17) is provided betweenthe pressure accumulator (15) and the external heat exchanger (4). 28.System according to claim 13, wherein the compression process is carriedout in two stages using a first stage compressor (1) and a second stagecompressor (1″) and that the discharge refrigerant from the first stageis directed into the intermediate pressure accumulator (15) before itenters the second stage compressor (1″).